Mechanisms of accumulation of arachidonate in phosphatidylinositol
in yellowtail
A comparative study of acylation systems of phospholipids in rat and the fish
species
Seriola quinqueradiata
Tamotsu Tanaka, Dai Iwawaki, Masahiro Sakamoto, Yoshimichi Takai, Jun-ichi Morishige,
Kaoru Murakami and Kiyoshi Satouchi
Department of Applied Biological Science, Fukuyama University, Japan
It is known that phosphatidylinositol (PtdIns) contains
abundant arachidonate and is composed mainly of 1-stea-
royl-2-arachidonoyl species in mammals. We investigated if
this characteristic of PtdIns applies to the PtdIns from
yellowtail (Seriola quinqueradiata), a marine fish. In common
with phosphatidylcholine (PtdCho), phosphatidylethanol-
amine (PtdEtn) and phosphatidylserine (PtdSer) from brain,
heart, liver, spleen, kidney and ovary, the predominant
polyunsaturated fatty acid was docosahexaenoic acid, and
levels of arachidonic acid were less than 4.5% (PtdCho),
7.5% (PtdEtn) and 3.0% (PtdSer) in these tissues. In striking
contrast, arachidonic acid made up 17.6%, 31.8%, 27.8%,
26.1%, 25.4% and 33.5% of the fatty acid composition of
PtdIns from brain, heart, liver, spleen, kidney and ovary,
respectively. The most abundant molecular species of PtdIns
in all these tissues was 1-stearoyl-2-arachidonoyl. Assay of
acyltransferase in liver microsomes of yellowtail showed that
arachidonic acid was incorporated into PtdIns more effect-
ively than docosahexaenoic acid and that the latter inhibited
incorporation of arachidonic acid into PtdCho without
inhibiting the utilization of arachidonic acid for PtdIns. This
effect of docosahexaenoic acid was not observed in similar
experiments using rat liver microsomes and is thought to

resolved.
Several enzymatic systems are involved in the accumu-
lation of arachidonate in PtdIns. CoA)1-acyl-2-lyso-PtdIns
acyltransferase activity, operating in the remodeling path-
ways of phospholipid biosynthesis, is known to utilize
arachidonoyl-CoA as substrate [15,16]. Both diacylglycerol
kinase [17–20] and CDP-sn-1,2-diacylglycerol synthase [21],
enzymes involved in the PtdIns cycle, have been reported to
contribute to the enrichment of arachidonate in PtdIns.
With respect to the biosynthesis of PtdIns, we and others
[22,23] have demonstrated that sciadonic acid (20:3,
D-5c,11c,14c), an n)6 series trienoic acid that lacks the D8
double bond of arachidonic acid, is metabolized in a similar
manner to arachidonic acid in the biosynthesis of PtdIns
[24,25]. We have also presented evidence suggesting that the
nonarachidonic acid and utilizable polyunsaturated fatty
Correspondence to T. Tanaka, Department of Applied Biological
Science, Fukuyama University, Fukuyama, 729-0292, Japan.
Fax: + 81 84 936 2459, Tel.: + 81 84 936 2111, Ext. 4056,
E-mail:
Abbreviations: PKC, protein kinase C; PtdCho, phosphatidylcholine;
PtdEtn, phosphatidylethanolamine; PtdIns, phosphatidylinositol;
PtdSer, phosphatidylserine; PUFA, polyunsaturated fatty acid.
Enzymes: acylCoA:lysophospholipid acyltransferase (EC 2.3.1.23);
CDP-diacylglycerol synthase (CTP-phosphatidate:cytidylyltrans-
ferase; EC 2.7.7.41); diacylglycerol kinase (EC 2.7.1.107); phospho-
lipase A
2
(EC 3.1.1.4); phospholipase C (EC 3.1.4.3); protein kinase C
(EC 2.7.1.37).

enoic acid and that several acyltransferase activities are
involved in the process in yellowtail.
Materials and methods
Materials
Yellowtails (S. quinqueradiata) were obtained from a
local market. Standard fatty acids were purchased from
Serdary Research Laboratories (London, ON, Canada).
[1-
14
C]Arachidonic acid (55 mCiÆmmol
)1
)and[1-1
4
C]doco-
sahexaenoic acid (55 mCiÆmmol
)1
) were from NEM Life
Sciences Products, Inc. (Boston, MA, USA). Essentially
fatty acid-free BSA, ATP, CoA, 1-palmitoyl-2-lyso-phos-
phatidylcholine (lysoPtdCho), phospholipase C (from
Bacillus cereus) and phospholipase A
2
(from Crotalus
adamanteus venom) were from Sigma Chemical Co.
(St Louis, MO, USA). By treatment with phospholipase
A
2
[30], 1-acyl-2-lyso-PtdIns (lysoPtdIns) was prepared
from bovine liver PtdIns (Sigma). The resulting lysoPtdIns
was purified by TLC using chloroform/acetone/methanol/

the same method as those of yellowtail.
Acyltransferase assay
The isolated liver of yellowtail was homogenized in 50 m
M
potassium phosphate buffer (pH 7.0) containing 1.5 m
M
glutathione, 0.15
M
KCl, 1 m
M
EDTA and 0.25
M
sucrose
(homogenizing buffer) with a Potter–Elvehjem glass/Teflon
homogenizer. The microsome fraction was prepared by
sequential centrifugation [25]. Microsomes from the liver of
male Sprague–Dawley rats (250–300 g) were prepared by
the same method. The final microsomal pellet was suspen-
ded in the homogenizing buffer (omitting EDTA), and the
protein content was determined by the method of Lowry
et al. [33]. Acyltransferase was assayed as described previ-
ously [25]. Each incubation contained 32 nmol lysoPtdCho
(1-acyl) or lysoPtdIns (1-acyl), 0.5 m
M
nicotinamide,
1.5 m
M
glutathione, 0.15
M
KCl, 5 m

were investigated (Tables 1–4). In all the tissues, the most
abundant PUFA in the PtdCho fraction was docosahexa-
enoic acid. The proportion of eicosapentaenoic acid in
PtdCho was relatively high compared with that in PtdEtn
Ó FEBS 2003 Arachidonate in phosphatidylinositol of yellowtail (Eur. J. Biochem. 270) 1467
and PtdSer, except in brain where oleic acid was abundant.
In both the PtdEtn and PtdSer fractions, docosahexaenoic
acid was the predominant PUFA in all the tissues. The
presence of dimethylacetals in PtdEtn suggested the exist-
ence of a substantial amount of an alkenylacyl subclass in
these tissues. In common with PtdCho, PtdEtn and PtdSer,
levels of arachidonic acid were very low compared with
those of docosahexaenoic acid in these tissues. In striking
contrast, larger amounts of arachidonic acid existed in
PtdIns from all tissues investigated (Fig. 1). The propor-
tion of it in PtdIns was highest in ovary (33.5%) and
lowest in brain (17.6%). In all tissues, the proportion of
Table 3. Fatty acid composition of PtdSer from various tissues of yellowtail. Values are weight percentages, given as the mean ± SD. Tissues were
obtained from three different yellowtails.
Fatty acid Brain Heart Liver Spleen Kidney Ovary
14:0 0.7 ± 0.3 0.9 ± 1.0 0.5 ± 0.2 0.8 ± 0.2 0.4 ± 0 0.4 ± 0.7
16:0 2.7 ± 1.6 7.2 ± 2.0 16.7 ± 3.2 6.3 ± 0.9 11.1 ± 2.0 8.5 ± 2.4
16:1 1.8 ± 1.0 1.3 ± 1.3 0.4 ± 0.2 1.6 ± 0.7 0.5 ± 0.3 0.4 ± 0.2
18:0 26.4 ± 2.4 31.3 ± 4.9 25.7 ± 3.4 32.0 ± 1.3 28.8 ± 1.1 31.7 ± 3.0
18:1(n)9) 19.6 ± 2.2 4.2 ± 0.7 3.3 ± 1.1 4.4 ± 1.3 4.2 ± 1.5 7.6 ± 3.1
18:1(n)7) – 2.5 ± 0.5 1.6 ± 0.2 3.2 ± 0.3 2.4 ± 0.4 2.8 ± 0.6
18:2(n)6) 2.1 ± 2.3 0.7 ± 0.4 – 2.1 ± 2.2 0.6 ± 0.3 0.7 ± 0.2
20:4(n)6) 0.5 ± 0.2 0.9 ± 0.4 1.4 ± 1.0 1.1 ± 0.3 2.0 ± 0.6 3.0 ± 2.0
20:5(n)3) 0.9 ± 0.1 1.5 ± 0.6 1.0 ± 0.2 1.5 ± 0.7 2.6 ± 2.0 1.5 ± 1.0
22:5(n)3) 4.3 ± 1.5 4.1 ± 0.8 2.1 ± 0.5 2.2 ± 0.7 2.8 ± 0.6 2.8 ± 1.2

22:5(n)3) 1.3 ± 0.2 4.0 ± 0.3 1.8 ± 0.7 2.1 ± 0.8 1.7 ± 0.6 1.5 ± 0.7
22:6(n)3) 19.2 ± 4.9 41.5 ± 5.0 39.1 ± 4.5 37.7 ± 1.9 32.9 ± 3.7 27.4 ± 4.3
1468 T. Tanaka et al.(Eur. J. Biochem. 270) Ó FEBS 2003
docosahexaenoic acid in PtdIns was lower than in other
phospholipids in corresponding tissues.
Fatty acid compositions of PtdCho, PtdEtn, PtdSer and
PtdIns from brain, heart, lung, liver, pancreas, kidney and
testis of rat were investigated. Only the proportions of
arachidonic acid in each phospholipid are presented in
Fig. 1. The proportions of arachidonic acid in PtdCho,
PtdEtn and PtdSer from these rat tissues varied from
4.7% to 21.4%, from 10.6% to 39.1% and from 4.8% to
32.6%, respectively. In contrast, 38.5%, 33.6%, 38.7%,
32.9%, 36.2% and 34.7% of total fatty acids in the
PtdIns of rat brain, heart, lung, liver, pancreas, kidney
and testis, respectively, were arachidonic acid. These
results confirm that PtdIns is rich in arachidonic acid in
rat tissues. Furthermore, it is evident that this characteri-
stic of PtdIns also applies to yellowtail, a fish species
living in seawater.
Molecular species composition of PtdIns from tissues
of yellowtail and rat
The molecular species compositions of PtdIns from various
tissues of yellowtail were analyzed by HPLC as diacyl-
glyceroldinitrobenzoyl derivatives. To assign major peaks of
these derivatives, we collected the eluate corresponding to
each molecular species peak, and directly analysed the fatty
acids of each fraction by GC. Under our analytical
conditions, one pair of molecular species, 18:1/22:6 and
16:0/20:5, could not be resolved. Therefore, the amounts of

PtdIns in fish cells. To investigate this, we assessed the
efficacy of the acylation of [
14
C]arachidonic acid or
[
14
C]docosahexaenoic acid into sn-2 of lysoPtdIns (1-acyl)
or lysoPtdCho (1-acyl) in fish liver microsomes. In prelimi-
nary experiments, the optimum temperature for acylation of
arachidonic acid to lysophospholipids was found to be
37 °C, so the assay was conducted at this temperature.
When lysoPtdIns was used as an acyl acceptor, arachidonic
acid was incorporated into sn-2 of PtdIns more effectively
than docosahexaenoic acid (Fig. 2A). The saturation levels
of acylation for arachidonic acid and docosahexaenoic acid
were  70 and 7 nmol per 10 min per mg protein, respect-
ively. When lysoPtdCho was used as an acyl acceptor, the
acyltransferase activity of the fish liver microsomes acylated
docosahexaenoic acid more effectively than arachidonic
acid (Fig. 2B). At a fatty acid concentration of 50 l
M
,
the amounts of docosahexaenoic acid and arachidonic
acid incorporated into PtdCho were 129 and 94 nmol per
10 min per mg protein, respectively. The same experiments
were conducted with rat liver microsomes: docosahexaenoic
acid was found to be a poor acyl donor not only for
lysoPtdIns but also for lysoPtdCho compared with arachi-
donic acid (Fig. 2C,D). At a fatty acid concentration of
50 l

14
C]arachidonic
acid into lysophospholipid was investigated. This experi-
ment was conducted in the presence of both lysoPtdIns and
lysoPtdCho to elucidate the distribution of [
14
C]arachidonic
acid incorporated into these phospholipids. We also modi-
fied the experimental conditions so that the addition of an
equimolar quantity of unlabeled arachidonic acid achieved
50% inhibition of the acylation of [
14
C]arachidonic acid to
lysophospholipids. In experiments using microsomes from
yellowtail liver (Fig. 3A), the distribution of [
14
C]arachi-
donic acid between PtdCho and PtdIns was approximately
1 : 1 in the absence of docosahexaenoic acid. In contrast,
the addition of docosahexaenoic acid at equimolar, two and
fourtimesmolarexcessover[
14
C]arachidonic acid modified
the distribution of [
14
C]arachidonic acid between PtdCho
and PtdIns from 1 : 1 to 1 : 3, 1 : 4 and 1 : 5, respectively.
These results obtained in the presence of large amounts of
docosahexaenoic acid are in good agreement with the
distribution patterns of arachidonic acid between PtdCho

The key enzymatic activity for construction of the final
molecular species of PtdIns is considered to be acylCoA–
lysoPtdIns acyltransferase activity operating in the remode-
ling pathway of phospholipid biosynthesis. This enzymatic
activity in liver microsomes of yellowtail strictly recognized
arachidonic acid and hardly utilized docosahexaenoic acid
at all. This one-sided efficacy was remarkable compared
with that observed in rat liver microsomes. This strict
recognition must contribute to the accumulation of arachi-
donic acid in PtdIns in yellowtail.
Docosahexaenoic acid is predominantly acylated to
PtdCho in tissues of yellowtail like other marine fish species
[26–29,34]. Consistent with these observations, lysoPtdCho
acyltransferase activity in liver microsomes of the yellowtail
preferred docosahexaenoic acid. This enzymatic activity
also utilized arachidonic acid with significant efficacy.
Therefore, in the absence of docosahexaenoic acid, arachi-
donic acid was acylated into both lysoPtdCho and lyso-
PtdIns at similar levels (Fig. 3A). The result indicates that,
in yellowtail, there is no selectivity for incorporation of
Fig. 1. Arachidonic acid contents of PtdCho, PtdEtn, PtdSer and
PtdIns obtained from several tissues of yellowtail and rat.
1470 T. Tanaka et al.(Eur. J. Biochem. 270) Ó FEBS 2003
arachidonic acid itself, whether into PtdCho or PtdIns.
However, in the presence of a large amount of docosahexa-
enoic acid, docosahexaenoic acid effectively inhibits the
incorporation of arachidonic acid into PtdCho without
inhibiting the utilization of arachidonic acid for PtdIns
(Fig. 3A). A possible explanation of this phenomenon is
that docosahexaenoic acid competes with arachidonic acid

Microsomes (0.1 mg protein ) from liver of yellowtail (A) or rat (B)
were incubated at 37 °C for 10 min with 10 nmol labeled arachidonic
acid (*AA) and the indicated amount of unlabeled DHA in the pre-
sence of both 6.4 nmol 1-acyl-2-lyso-PtdIns and 6.4 nmol 1-acyl-
2-lyso-PtdCho. After the incubation, phospholipids were separated by
2D TLC, and radioactivity was measured. Therefore, only the amount
of arachidonic acid incorporated into each lysophospholipid could be
determined. Similar results were obtained in three independent
experiments with microsomes from different yellowtails or rats.
Table 5. Molecular species composition of PtdIns from various tissues of yellowtail. The isolated PtdIns was converted to dinitrobenzoyl derivative as
described in materials and methods and analyzed by HPLC. Values are mol percentages, given as the mean ± SD. Tissues were obtained from
three different yellowtails.
Molecular species Brain Heart Liver Spleen Kidney Ovary
18:1/20:5(n)3) 5.8 ± 1.9 2.5 ± 0.3 3.6 ± 1.0 2.5 ± 1.1 1.6 ± 1.5 1.5 ± 0.4
18:1/22:6(n)3)+16:0/20:5(n)3) 11.5 ± 2.5 3.1 ± 1.0 4.1 ± 1.0 4.6 ± 2.3 4.7 ± 4.4 4.6 ± 1.1
16:0/22:6(n)3) 6.2 ± 1.2 1.0 ± 0.5 1.7 ± 1.5 2.3 ± 1.2 1.4 ± 1.3 2.7 ± 1.4
18:1/20:4(n)6) 9.1 ± 1.6 9.9 ± 0.2 9.4 ± 2.5 6.9 ± 1.3 6.8 ± 0.8 8.8 ± 2.7
16:0/20:4(n)6) 7.3 ± 2.2 4.7 ± 0.6 4.7 ± 1.8 4.9 ± 3.0 3.3 ± 1.6 6.7 ± 2.7
18:0/20:5(n)3) 16.7 ± 0.1 17.6 ± 3.4 18.9 ± 4.8 15.0 ± 6.3 15.5 ± 6.3 9.0 ± 4.6
18:0/22:6(n)3) 11.8 ± 1.8 1.9 ± 0.5 3.0 ± 3.2 9.4 ± 4.8 5.3 ± 1.3 8.6 ± 4.2
18:0/20:4(n)6) 19.8 ± 2.6 54.8 ± 1.2 44.4 ± 5.5 45.4 ± 5.9 31.9 ± 4.1 47.4 ± 6.4
Fig. 2. Incorporation of [
14
C]arachidonic acid or [
14
C]docosahexaenoic
acid (DHA) into exogenously added lysoPtdCho or lysoPtdIns in
microsomes from liver of yellowtail or liver of rat. The incubation was
conducted at 37 °Cfor10minwith0.1mgproteinfrommicrosomes
of yellowtail liver in the presence of 32 nmol 1-acyl-2-lyso-PtdIns (A)

of diacylglycerol derived from inositolphospholipid [38].
PKC isoforms that can be activated by diacylglycerol have
been reported to exist even in fish cells [39,40]. The
molecular conservation of PtdIns gives rise to the unifica-
tion of diacylglycerol molecular species produced in
response to agonistic stimulation. It is still unclear whether
PKC discriminates the structural difference between
1-stearoyl-2-arachidonoylglycerol and other PUFA-
containing diacylglycerol molecular species. Bell & Sargent
[40] have reported that n)3-rich diacylglycerols prepared
from cod roe have a similar potency to 1-stearoyl-
2-arachidonoylglycerol for increasing PKC activity in vitro.
Similar results have been reported with synthetic 1-stearoyl-
2-docosahexaenoylglycerol [41]. On the other hand, evi-
dence has emerged that activation of PKC is dependent
on the composition of diacylglycerol molecular species
[38,42,43] and that diacylglycerols containing PUFAs, such
as arachidonic acid and mead acid (20:3, D-5c,8c,11c), are
more potent activators of PKC [44]. In addition, 1-stearoyl-
2-arachidonoylglycerol has been reported to be a more
potent activator of PKC than diacylglycerols rich in n)3
series PUFA under certain conditions [45]. It has been
reported that 1-stearoyl-2-arachidonoylglycerol attains a
V-shaped conformation in biological membranes that
facilitates anchoring of PtdSer-requiring proteins [46].
Furthermore, some Ca
2+
channels that mediate the influx
of Ca
2+

platelets in vivo and in vitro. J. Lipid Res. 26, 457–464.
2. Connor, W.E., Neuringer, M. & Lin, D.S. (1990) Dietary effects
on brain fatty acid composition: the reversibility of n-3 fatty acid
deficiency and turnover of docosahexaenoic acid in the brain,
erythrocytes, and plasma of rhesus monkeys. J. Lipid Res. 31,
237–247.
3. Berger, A. & German, J.B. (1990) Phospholipid fatty acid com-
position of various mouse tissues after feeding a-linolenate
(18:3,n)3) or eicosatrienoate (20:3,n)3). Lipids 25, 473–480.
4. Mori, T.A., Codde, J.P., Vandongen, R. & Beilin, L.J. (1987) New
findings in the fatty acid composition of individual platelet phos-
pholipids in man after dietary fish oil supplementation. Lipids 22,
744–750.
5. Ahmed, A.A., Celi, B., Ronald, K. & Holub, B.J. (1989) The
phospholipid and fatty acid compositions of seal platelets: a
comparison with human platelets. Comp. Biochem. Physiol. 93B,
119–123.
6. Kurvinen, J P., Kuksis, A., Sinclair, A.J., Abedin, L. & Kallio, H.
(2000) The effect of low a-linolenic acid diet on glycerophospho-
lipid molecular species in guinea pig brain. Lipids 35, 1001–1009.
7. Jungalwala, F.B., Evans, J.E. & McCluer, R.H. (1984) Compo-
sitional and molecular species analysis of phospholipids by high
performance liquid chromatography coupled with chemical ioni-
zation mass spectrometry. J. Lipid Res. 25, 738–749.
8. Patton, G.M., Fasulo, J.M. & Robins, S.J. (1982) Separation of
phospholipids and individual molecular species of phospholipids
by high-performance liquid chromatography. J. Lipid Res. 23,
190–196.
9. Takamura, H., Narita, H., Park, H.J., Tanaka, K., Matsuura, T.
& Kito, M. (1987) Differential hydrolysis of phospholipid mole-

17. MacDonald, M.L., Mack, K.F., Williams, B.W., King, W.C. &
Glomset, J.A. (1988) A membrane-bound diacylglycerol
kinase that selectively phosphorylates arachidonoyl-diacylglycerol.
J. Biol. Chem. 263, 1584–1592.
18. Lemaitre, R.N., King, W.C., MacDonald, M.L. & Glomset, J.A.
(1990) Distribution of distinct arachidonoyl-specific and non-
specific isoenzymes of diacylglycerol kinase in baboon (Papio
cynocephalus)tissues.Biochem. J. 266, 291–299.
19. Walsh, J.P., Suen, R., Lemaitre, R.N. & Glomset, J.A. (1994)
Arachidonoyl-diacylglycerol kinase from bovine testis. J. Biol.
Chem. 269, 21155–21164.
20. Tang, W., Bunting, M., Zimmerman, G.A., McIntyre, T.M. &
Prescott, S.M. (1996) Molecular cloning of a novel human dia-
cylglycerol kinase highly selective for arachidonate-containing
substrates. J. Biol. Chem. 271, 10237–10241.
21. Saito, S., Goto, K., Tonosaki, A. & Kondo, H. (1997) Gene
cloning and characterization of CDP-diacylglycerol synthase from
rat brain. J. Biol. Chem. 272, 9503–9509.
22. Berger, A. & German, J.B. (1991) Extensive incorporation of
dietary D-5,11,14 eicosatrienoate into the phosphatidylinositol
pool. Biochim. Biophys. Acta 1085, 371–376.
23. Berger, A., Fenz, R. & German, J.B. (1993) Incorporation of
dietary 5,11,14-icosatrienoate into various mouse phospholipid
classes and tissues. J. Nutr. Biochem. 4, 409–420.
24. Tanaka, T., Takimoto, T., Morishige, J., Kikuta, Y., Sugiura, T.
& Satouchi, K. (1999) Non-methylene-interrupted poly-
unsaturated fatty acids: effective substitute for arachidonate of
phosphatidylinositol. Biochem. Biophys. Res. Commun. 264,
683–688.
25. Tanaka, T., Morishige, J., Takimoto, T., Takai, Y. & Satouchi, K.

Tanaka, T. (1994) Lysophosphatidylcholine from white muscle of
bonito Euthynnus pelamis (Linnaeus): involvement of phospho-
lipase A
1
activity for its production. Biochim. Biophys. Acta 1214,
303–308.
35. Inoue, M., Murase, S. & Okuyama, H. (1984) Acyl coenzyme A:
phospholipid acyltransferases in porcine platelets discriminate
between x-3 and x-6 unsaturated fatty acids. Arch. Biochem.
Biophys. 231, 29–37.
36. Chilton, F.H., Fonteh, A.N., Surette, M.E., Triggiani, M. &
Winkler, J.D. (1996) Control of arachidonate levels within
inflammatory cells. Biochim. Biophys. Acta 1299, 1–15.
37. de Renobales, M., Cripps, C., Stanley-Samuelson, D.W., Jurenka,
R.A. & Blonquist, G.J. (1987) Biosynthesis of linoleic acid in
insects. Trends. Biochem. Sci. 12, 364–366.
38. Leach, K.L., Ruff, V.A., Wright, T.M., Pessin, M.S. & Raben,
D.M. (1991) Dissociation of protein kinase C activation and
sn-1,2-diacylglycerol formation. J. Biol. Chem. 266, 3215–3221.
39. Berglund, K., Midorikawa, M. & Tachibana, M. (2002) Increase
in the pool size of releasable synaptic vesicles by the activation of
protein kinase C in goldfish retinal bipolar cells. J. Neurosci. 22,
4776–4785.
40. Bell, M.V. & Sargent, J.R. (1987) Protein kinase C activity in the
spleen of trout (Salmo gairdneri) and the rectal gland of dogfish
(Scyliorhinus canicula), and the effects of phosphatidylserine and
diacylglycerol containing (n-3) polyunsaturated fatty acids. Comp.
Biochem. Physiol. 87B, 875–880.
41. Marignani, P.A., Epand, R.M. & Sebaldt, R.J. (1996) Acyl
chain dependence of diacylglycerol activation of protein